[tambourine_man]

I’d like to know the name of this alternative that’s as feature-rich and yet bullet-proof while still being open source

[rastographics]

it's called processwire and once I found it I never looked back

[PrimeMcFly]

Django and Wagtail is one option. Do a little research and you'll find others.

[vdaea]

Neither are written in PHP so they don't work on most cheap hostings.

[PrimeMcFly]

You can get a kimsufi server for $6/month, and there is plenty of cheap hosting offering django, pretty sure you can even find python hosting for free up until a point.